Experimental investigations on single-phase convection and two-phase flow boiling heat transfer in an inclined rod bundle

Highlights: • Local single-phase convective coefficients in inclined tube bundles were obtained. • The effects on flow boiling heat transfer in inclined rod bundles were analyzed. • A new Chen-type correlation was developed to predict flow boiling heat transfer coefficients in inclined rod bundles. -- Abstract: Single-phase convection and steam-water two-phase flow boiling heat transfer experiments in an electrically heated 4 × 25 staggered inclined rod bundle were carried out for the following range: 15 kg m⁻² s⁻¹ ≤ G ≤ 50 kg m⁻² s⁻¹, 20.0 kW m⁻² ≤ q ≤ 55.0 kW m⁻², 0.05 ≤ x_out ≤ 0.79 and 117 kPa ≤ P_in ≤ 260 kPa. Single-phase convective results show that the independence principle can be applied to the case that all tubes were heated in inclined rod bundles. With respect to two-phase results, the local flow boiling heat transfer coefficient increases from the bottom row to the eleventh row and then can be considered as a constant value from the eleventh row to the top row. An increasing heat flux results in a decrease of the flow boiling heat transfer coefficient. However, no significant effects of mass velocity and quality were observed. The inclination angle has a small effect on the flow boiling heat transfer coefficient at low heat fluxes. However, when heat flux is high, the flow boiling heat transfer coefficient in the inclined rod bundle is the minimum while that in the vertical rod bundle is the maximum compared with that in the horizontal rod bundle. In a general, a Chen-type correlation was developed to predict 98.5 percent of local flow boiling heat transfer coefficient data in the inclined rod bundle with a maximum deviation of ±20%.